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SYDNEY - A case of mistaken identity may have led three teenage boys to punch and kick a New Zealand man to death on a Sydney sporting oval, a court has been told.

Christopher Leichester was on his way to a party in Woolooware in Sydney's south on Saturday night when he was set upon by a group of teenage boys as he crossed the oval, Parramatta Children's Court was told.

In an unprovoked attack, the boys allegedly punched the 20-year-old to the ground and kicked him several times in the head.

The savage assault severed an artery between his brain and central nervous system, as well as fracturing his cheekbone and causing a brain haemorrhage, according to a police statement of facts tendered to the court.

Mr Leichester, who had only been in Australia six months, died in hospital yesterday afternoon.

3News reported Mr Leichester's parents flew to Sydney yesterday.

Three 16-year-olds, from Menai, Connells Point and Narwee, all in Sydney's south, faced court today charged with his murder.

One of the boys sniffled and wiped his eyes during the hearing, while another hung his head and covered his face.

Court documents revealed the attack appeared to have occurred because the teenagers believed Mr Leichester had abused them as they drove away from Woolooware railway station a short time earlier.

But a witness told police it was two other men who chased and hurled abuse at the teenagers' car.

The documents said the boys aggressively approached Mr Leichester as he crossed the oval, demanding to know if he was "trying to start shit".

When he did not respond and tried to back away, one of the boys punched him under the chin, causing his head to snap back as he staggered backwards.

Another boy then allegedly punched him square in the face, knocking him to the ground.

"All three young people were standing over the victim at the time," the statement of facts alleged.

A witness told police there were then "four thuds in quick succession ... (then one of them) kicked the victim to the head causing a sickening thud".

In court today, each of the boys pleaded not guilty and applied for bail, which was opposed by police.

One of the accused is believe to be the brother of former NRL league star David Peachey.

Police prosecutor Phil Kraus said the boys knew many of the around 20 witnesses to the "unprovoked attack" and had contacted some of them prior to their arrest to tell them not to "snitch".

They were all refused bail by Magistrate Mark Richardson on the grounds that it was an offence of "significant violence" and there were no exceptional circumstances.

The boys were remanded in custody to reappear at the same court on December 6.

- AAP